This excitement among tourists at the Keibul Lamjao
National Park (KLNP) — the world's only floating reserve — in the north
east Indian state of Manipur is rather usual. The buzz is around the endangered and elusive Sangai or the Indian Eld's deer (Rucervus eldii eldii),
locally called the "dancing deer" for its dainty gait.

However, the Sangai, Manipur's state animal and a leitmotif of the state's art, culture
and folklore, is now critically threatened by untreated human waste that is making its way into the 40 square kilometre national park, the deer's last refuge. Liquid effluents, solid wastes and sewage from Manipur's capital city Imphal are invading the deer's abode through polluted rivers that empty into the national park.

Added to that, loss of genetic variability, inbreeding, genetic drift and catastrophic events like flood and diseases have rendered the animal critically endangered. Sangai is also included in Appendix 1 of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). The deer was actually thought to have gone extinct until a remnant population was rediscovered in 1950 at the south-eastern fringe of Manipur's Loktak lake.

A 90-minute drive from Imphal gets one to
Sendra, the highest point of the lake that offers a bird's eye-view of the
phumdis dotting the water body — beautiful rings of green stretching across the
clear blue expanse of the lake. These floating meadows take up to 20 years to
form and collectively house around 260 deer, whose elegant gait inspires
Manipuri dance moves and much of its folklore.

The islets are thinning due to water pollution and
untreated waste, making it tough for the deer to survive. About 65 per cent (26 square kilometre) of
the national park is covered with a thick and almost contiguous mat of floating
meadows.

Poor water quality

Loktak's water woes are mainly due to loss of vegetation
cover in its catchment and construction of a barrage on the lake's southern side. Poor water quality has altered the vegetation cover and
composition of the phumdis and hence their potential to sustain the Sangais. The construction of the Ithai Barrage in 1983 has impacted the lake's natural
flushing mechanism.

"The lake was a seasonally flooded wetland with several
small wetlands that separated during dry season and merged in monsoon,"
Tuboi explains. After the construction of the barrage, the water level in the
lake is maintained at a regular 769.12 metres above mean sea level so as to
support the hydro-power project. Tuboi says the lake is under stress due to
"permanent flooding". This does not allow the phumdis to settle on the
water bed during dry season or to pick up nutrients and soil to maintain the
desired thickness.

They found that Loktak lake was "severely polluted"
due to the influx of sewage and other wastes from these two rivers.
In addition, surface runoff from the surrounding agricultural and catchment
areas was also diminishing the lake's water quality, indicated by the high
nitrogen concentration.

Saving the Sangai

The researchers recommend setting up sewage treatment plants
at strategic locations, such as at the inlet channel at Toubul village, which
is surrounded by the lake. Meanwhile, Tuboi and his team have been surveying
spots within the lake where a satellite population of the Sangai could be
relocated.

"Sangai is the flagship species. If we save it, we save
everything else. Before the fragile balance between the lake ecosystem and the
local cultural practices is permanently lost, the lake needs to be restored by
improving its water quality and hydrological regime," Tuboi added.

Hope for the Sangai was recently rekindled when a team of researchers from Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) sequenced the deer's complete mitochondrial genome2. “The mitogenome sequence tells us that it is genetically distinct from other subspecies owing to its geographic isolation,” says Ajay Gaur, a principal scientists at CCMB's Laboratory for Conservation of Endangered Species (LaCONES).

Gaur and his colleagues took a crack at the Sangai mitochondrial DNA from a tissue sample and reported the 16, 357 base pair long mitogenome. A mitogenome analysis helps in comparing closely related organisms. Using several unique characteristics like maternal inheritance, high evolutionary rates, small genome size, conserved gene content, and lack of extensive recombination of mitochondrial genes, scientists use such sequences to track the evolutionary history of the animal and its speciation.

It is common conservation practice to create alternate homes for isolated, single-population species so that they are not wiped off from the face of earth if an epidemic or natural disaster strikes. The Manipur government is considering a proposal by its forest department to shift the species to a nearby fresh water lake Pumlenpat , the second largest in the state after Loktak, also replete with phumdis. However, this lake also faces unique challenges due to human settlements and encroachment, and it will be long before livelihood issues for local fisher folks are solved.

Till such time, the vulnerable floating meadows remain the Sangai's only home on earth.

[This article has been published with support from the TransDisciplinary University (TDU)-Nature India Media Fellowship in Science Journalism. The author can be contacted at sahana.g@ians.in]